1. Field of the Invention
The present invention relates to an optical and electrical circuit board, and a method of manufacturing the optical and electrical circuit board.
2. Discussion of the Background
In recent years, the amount of communication data of the Internet or the like is increasing dramatically, and a technology for realizing high-speed and large capacity communication using an optical signal by converting an electrical signal in a signal processor and an optical signal transmitted through an optical fiber to each other become increasingly important.
An optical and electrical circuit board having a structure that a microlens condensing an optical signal is disposed between an optical signal receiving/transmitting element and an optical waveguide in order to convert an electrical signal and an optical signal to each other, has been proposed.
Methods of forming such a microlens include a method using a mold, a forming method by dropping lens material, a method of forming a lens by heating and softening lens material cylindrical shaped, a method of exposing lens material to exposure light which has passed through a mask. In each of the conventional manufacturing methods, a microlens is formed separately from an optical and electrical circuit board and is mounted on the optical and electrical circuit board, so that the cost of mounting the microlens is high and alignment of the microlens to the substrate is difficult.
A method of forming a microlens using a mask is described in, for example, Japanese Patent Application Laid-open No. 8-286002. The contents of Japanese Patent Application Laid-open No. 8-286002 are incorporated herein by reference in their entirety.